Much like with addition, this week we have been exploring multiple strategies for solving subtraction problems. As we begin to explore the relationship between addition and subtraction, I find that understanding how to represent and solve a problem in a variety of ways strengthens the depth of mastery over the concept. We had a few of those wonderful "Ah hah!" moments with modeling subtraction using counting cubes and a number line as our first instinct may seem to be going right to the standard algorithm to solve tricky subtraction problems.

We also focused a lot on borrowing and regrouping within subtraction. Thinking back to when I was taught subtraction, I remember learning the steps to regrouping without fully understanding what was actually going on within the problem. Hoping to show the standard algorithm steps side by side with counting cubes, I am working to bridge the understanding of how borrowing works. This requires a mastery of place value, knowing that 4 tens is equal to 3 tens and 10 ones, along with a foundational understanding of subtraction in which the numbers cannot switch places like they can in addition. I hope to continue to model borrowing across zeros using counting cubes in hopes that they make sense of the crazy crossing out and regrouping going on in their work.

As a part of estimation and checking our answer for reasonableness, we also covered a few strategies for rounding to the nearest 10, 100, or 1,000. Conceptual understanding can be shown using a number line while a step by step process is sometimes helpful for quick rounding. Lastly, for fun I told them a story method of understanding rounding using a worker and a boss. See if they can retell the story to you as a strategy for rounding!

We also covered multiple strategies to present and solve addition problems. Knowing and being able to use and explain multiple strategies helps strengthen the brain and we had a few amazing "Ah hah!" moments when exploring the many ways we can represent addition. The last method that is not on the anchor chart is the standard algorithm to solving addition (or "stacking" as they like to call it), which we went over as well! Next up is subtraction and understanding the relationship between the two Math operations!